This invention relates to a strain relief grommet. More particularly, this invention relates to grommet made of a thermoplastic synthetic resin such as nylon and used in fastening a power supply cord onto a perforation bored such as in a chassis of an electric appliance, for the purpose of ensuring insulation of the cord from the chassis, preventing the coat of the cord from being damaged by the abrasion thereof against the edge of the perforation and protecting the cord from being pulled out of electric contact with the electric appliance by an external force applied thereto.
Various suggestions have been made concerning grommets of this type. Generally grommets of this type are composed of two members which are adapted to firmly hold the cord passed therebetween when they are coupled into embracing engagement and the cord, by virtue of this firm grip by the two members, is fastened against the perforation bored in the chassis. In the grommet proposed heretofore, a depression is formed in one of the two members and a protrusion is formed on the other member so that the depression and the protrusion are brought into matched engagement by coupling the two members with each other and the cord passed therebetween is forcibly bent and fastened in position in the shape of a crank or wave.
In the grommet of the aforementioned construction, however, since the cord is bent in the shape of a crank or wave in an extremely short space in which the cord passes the members of a limited length, excessive strain develops in the cord and causes the coat of the cord to peel off or, occasionally, the core wires are broken. Particularly since the catching claws formed on the outer surface of the two members are forcibly passed through the perforation in the chassis and brought into biting engagement therewith when the grommet is to be attached to said perforation, the force with which the cord is bent is increased more than is necessary and the possibility of breaking the cord is proportionally increased.
An object of this invention is to provide a grommet which is capable of preventing the cord passed therein from freely moving in the direction of its length without requiring the cord to be forcibly bent.
Another object of this invention is to provide a grommet which is designed to facilitate the work of cord gripping and the work of fastening the grommet into the perforation such as in the panel.